Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Section 5A, 5B and 5C Abdominal Anatomy and Digestive System > Large Intestine > Flashcards

Large Intestine Flashcards

1
Q

What are the 8 different components of the large intestine / colon?

A 
Caecum
Appendix
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
Anus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 functions of the large intestine

A
  1. digestion
    - minimal
    - enteric bacteria ferment some indigestible carbohydrates and synthesize vitamin B and K
  2. absorption
    - most remaining water
    - electrolytes
    - vitamins produced by bacteria
  3. Propulusion
    - haustral contractions and mass movements propel faeces to rectum
  4. Defecation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 types of contractions in the LI?

A

Haustral contractions:

  • every 30 minutes
  • short lived slow contractions
  • mostly in ascending and transverse colon
  • initiated by ENS when individual haustra fill with food

Mass movements:

  • 3 to 4 times daily
  • powerful prolonged contractile waves
  • gastrocolic reflex: presence of food in stomach produces reflex mass movement
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the gastrocolic reflex?

A
  • presence of food in stomach produces reflex mass movement to propel food in large intestine towards rectum
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the defecation reflex?

A
  • mass movement of faeces into rectum stimulates visceral afferent neurons (distension)
  • visceral afferents initiates PNS spinal reflex at S2-4
  • PNS initiates contraction of rectum, and relaxation of internal anal sphincter
  • message also reaches brain to allow conscious decision on relaxation of external anal sphincter
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the caecum including the location, ileocecal junction, nerve supply, and vascular supply

A

Anatomy:

  • first part of LI
  • between ileum of SI and ascending colon
  • 7.5 cm length and breadth

Location:

  • right inguinal region
  • corresponds to right iliac fossa

Ileocecal junction:

  • ileocecal vavle controls passage of chyme through ileocecal orifice
  • formed by superior and inferior ileocecal folds

Vascular:

a. ileocolic artery (terminal branch of SMA)
b. ileocolic vein (drains to SMV)

Neuro:

  • PNS: CNX Vagus
  • SNS: abdominopelvic planchnic (lower Tx segments)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the appendix including anatomy, function, vascular and innervation

A

Anatomy:

  • arises from posteromedial aspect of caecum
  • inferior to ileocaecal junction
  • 6-10cm length
  • intraperitoneal
  • small twisted lumen (susceptible to blockage)

Function:

a. immunity: contains masses of lymphoid tissue, produces and stores lymphocytes
b. reservoir for beneficial gut bacteria

Neuro:
- visceral afferents (enter at T10)

Vascular:

a. appendicular a (branch of ileocolic from SMA)
b. ileocolic v (to SMV)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the anatomy of the ascending, transverse and descending colon

A

Ascending:

  • between caecum and right colic / hepatic flexure
  • secondarily retroperitoneal (covered by peritoneum anteriorly and laterally)

Transverse:

  • 45cm long
  • crosses abdo wall at level of umbilicus
  • largest and most mobile section of LI
  • between right colic / hepatic flexure and left colic / splenic flexure
  • two ligaments (phreniocolic to diaphragm and transverse mesocolon)

Descending:

  • between left colic / splenic flexure and sigmoid colon
  • retroperitoneal (covered anteriorly and laterally)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Describe the sigmoid colon

A
  • S shaped loop
  • inferior continuation of descending colon
  • 40cm long
  • extends from iliac fossa to rectum at S3
  • intraperitoneal

Rectosigmoid junction: signified by termination of teniae coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the rectosigmoid junction?

A

The junction between the sigmoid colon and the rectum at approx S3

  • signified by the termination of teniae coli
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 4 histological features of the large intestine?

A

Teniae coli:

  • 3 separate thickened bands of muscle in the longitudinal mm layer of muscularis
  • extend from caecum to beginning of rectum
  • muscular tone puckers colonic wall into haustra

Haustra:
- pocket like sacs in walls of LI

Crypts:

  • in mucosal layer of LI
  • contain goblet cells that produce mucous to protect LI wall and ease faecal passage

Omental / epiploic appendices:
- small fatty projections of omentum hanging from surface of colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the arterial supply of the LI?

A

Ascending colon and hepatic flexure:

  • branches from SMA
  • ileocolic and Rt colic a (from SMA)

Transverse colon:

  • middle colic a (SMA)
  • Rt colic a (SMA)
  • Lt colic a (IMA)

Descending colon:
- Lt colic
- superior sigmoid
(both from IMA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which components of teh LI are supplied by branches of the SMA, and which from the IMA?

A

SMA:

  • ascending colon
  • hepatic flexure

IMA:

  • descending colon
  • sigmoid colon

Both:
- transverse colon

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 4 branches of the SMA that supply the LI?

A
  1. Multiple intestinal branches of SMA (ascending colon)
  2. Ileocolic (ileocaecal junction, caecum)
  3. Right colic (ascending, hepatic flexure, part of transverse)
  4. Middle colic (transverse)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 branches of the IMA that supply the LI?

A
  1. Left colic (transverse and descending)

2. Superior sigmoid aa (sigmoid colon)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the venous drainage of the LI?

A

Draining into SMV:

  • ascending colon and hepatic flexure (branches of SMV, ileocolic and Rt colic)
  • transverse (SMV)

Draining into IMV:
- descending and sigmoid

17
Q

What is the innervation of the LI?

A

Ascending colon, hepatic flexure and transverse colon:

  • PNS: CNX Vagus
  • SNS: T10-12

Descending and sigmoid:

  • PNS: pelvic splanchnic (S2-4)
  • SNS: Lx part of sympathetic trunk and superior hypogastric plexus
18
Q

What is the anorectal flexure?

A

the sharp postero-inferior angle at the terminal rectum, between the rectum and the anus (at tip of coccyx)

19
Q

What are the peritoneal reflections of the rectum in males and females?

A

Females:

  • rectouterine pouch (pouch of Douglas)
  • peritoneum reflecting from rectum to posterior vagina and uterus

Males:

  • retrovesicle pouch
  • peritoneum reflecting from rectum to posterior bladder
20
Q

Describe the anatomy of the rectum

A
  • between sigmoid colon (S3) and anus (tip of coccyx)
  • rectal ampulla = dilated distal part of rectum directly above pelvic floor, relaxes to accomodate faecal mass
  • puborectalis m forms a sling around inferior rectum and has a role in maintaining continence
21
Q

Describe the vascular and neuro supply of the rectum

A

Arterial:
- branches of IMA (superior rectal, middle rectal, internal rectal)

Venous:

  • superior rectal v (into portal system)
  • middle and inferior rectal v (into systemic)

Neuro:

  • intrinsic: ENS
  • PNS: pelvic splanchnic (S2-4)
  • SNS: Lx part of sympathetic trunk and superior hypogastric plexus
22
Q

Describe the anatomy of the anal canal, including location, histology and features

A

Location:

  • terminal aspect of LI
  • between pelvic diaphragm and anus
  • begins at tip of coccyx and descends 2-3cm

HIstology:

  • rectal: simple columnar
  • anal: stratified squamous

Features:

  • anal columns: longitudinal folds of mucosa
  • anal sinuses: recesses bw columns that exude mucous when compressed by faeces
  • anal sphincters: internal (involuntary control) and external (voluntary control)
  • pectinate line: junction between superior and inferior anal canal, different neurovascular supply
23
Q

Describe the innervation and vascular supply of the anal canal

A

Arterial:

  • superior to pectinate line: superior rectal (from IMA)
  • inferior to pectinate line: inferior rectal (from internal iliac)

Venous:

  • superior to pectinate ine: internal rectal plexus (to superior rectal, IMV and portal system)
  • inferior to pectinate line: internal rectal plexus (to inferior rectal and caval system)

Neuro:

  • superior to pectinate line: inferior hypogastric plexus, PNS S2-4, visceral afferents
  • inferior to pectinate line: somatic motor and sensory from pudendal (S2-4), sensitive to pain, touch and temperature

Section 5A, 5B and 5C Abdominal Anatomy and Digestive System (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions